With recent improvements in functionality and versatility of electronic apparatuses, the electronic apparatuses include various devices such as semiconductor chips, sensors, and display devices. A large number of data are exchanged among these devices, and amounts of the data have been increased with improvements in functionality and versatility of the electronic apparatuses. Therefore, data are frequently exchanged with use of, for example, a high-speed interface capable of transmitting and receiving data at several Gbps.
To improve communication performance in the high-speed interface, emphasis (pre-emphasis or de-emphasis) and an equalizer are frequently used. The pre-emphasis is used to emphasize a high-frequency component of a signal in advance during transmission (for example, refer to PTL 1), and the de-emphasis is used to reduce a low-frequency component of a signal in advance during transmission. Moreover, the equalizer is configured to increase a high-frequency component of a signal during reception. Accordingly, in communication systems, an influence of signal attenuation by a transmission path is allowed to be reduced, and an improvement in communication performance is allowed to be achieved.